Apparatus for illustrating the motion oe pendulums upon the earth s



G. M. DIMMOGK. $011001 APPARATUS T0 ILLUSTRATE THE ROTATION 0P THBEARTH BY MEANS OF THE VIBRATIONS OF A PENDULUM.

Patented-July 12, 1853.

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UNITED STATES PATENT OEFTCE.

GEO. M. DIMMOCK, OE SPRINGFIELD, MASSACHUSETTS.

APPARATUS FOR ILLUSTRATING THE MOTION 0F PENDULUMS UPON THE EARTHS SURFACE.

Specification of Letters Patent No. 9,839, dated July 12, 1853.

To all whom it may concern:

Be it known that I, GEORGE M. DIMMOCK, of Springfield, in the county of Hampden, State of Massachusetts, have invented a new and useful Improvement to Illustrate the Rotation of the Earth by Means of the Vibrations of a Pendulum on an Artificial Globe, which I call the Foucaulator, and I do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same; and I refer to the annexed drawings, making a part of this specification, in which- Figure 1 is an elevation of the globe showing the pendulum attachment in perspective; Fig. 2 is a section.

The same letters indicate like parts on both of the figures.

A, is a common artificial globe.

B, is the stand with a. stem entering into the globe which supports it and upon which the globe revolves.

C, is the stand or tower upon which the pendulum is hung or suspended.

D, is the nut or thumb screw for moving and fastening the tower at any required latitude.

E, is the dial the center of which is on a line between the top of the tower and the center of the globe with the principal points of the compass marked on it to show more plainly to the eye the independent movement of the pendulum. The arm that sup ports the dial extends under the thumb nut to the tower and answers for a washer to the same.

F, is the band or starp which supports the tower and upon which the tower is moved from the pole to the Equator.

G, G, are two plugs driven firmly into the globe with the heads projecting, forfirmly fastening the ends of the band on.

H is the crank for turning the globe which is fastened bet-ween the top plug head and band. One screw secures both crank and band.

I, is a pendulum firmly secured in the point of ,the conical head of a bolt which passes through the top of the tower and fastens with a thumb nut. I use a different pendulum for different latitudes, thependulum rods I generaly make of fine brass wire, rolling them between two smooth steel plates to give them evenness of elasticity so as to form delicate springs not having a tendency to bend one way more than another. For any latitude between the poles I bend or spring the pendulum rods to overcome the gravity of the earth so when at rest they will hang on the line from the point of suspension and the center of the globe, terminating in a ball directly over the center of the dial.

J, is the catch to hold the pendent terminus of the, pendulums from over the dial ready to release and set them to vibrating when the globe is revolving. This catch is attached to the tower by two points, one on the inside of the end of each prong entering two sockets, one on each side of the tower, the prongs being bent together a little and the points sprung into the sockets so that it will rise and fall easy.

K is an elbow lever the fulcrum of which is attached to the globe near the bottom, the long arm extending under the lower end of the strap.

L, is a circular plate firmly secured to the stand B and is cut out on the edge so that the short arm of the lever by resting against the edge will rise slow and then fall, by turning the globe on the stand.

M, is a spring to bear on the lever.

N, is a narrow braid or string leading from the cat-ch J to the end of the long arm of the lever K, where it passes under a spring which holds it lightly so that it may be slipped either way.

The operation of this machine is as fol lows: Take a pendulum for any degree of latitude and fasten it firmly to the top of the tower with the bolt and thumb nut; then with the thumb nut D, move the tower so that the pendulum ball will hang over the center of the dial; then turn the globe until the lever K falls to its lowest point on the plate L; then take hold of the string N, below the lever and pull down gently until the catch J, rests on the thumb nut D, then turn the globe until the lever rises, then bend the pendulum toward the tower and raise the catch so that it will hold the pendulum by the ball; then turnthe globe gently by the crank H and when the lever falls it pulls down the catch with the string and that sets the pendulum to vibrating, and as the globe moves around, it illustrates the principle plainly to the eye, by the change of the vibrations of the pendulum relatively to the degrees of the dial.

suspension, and the center of the globe; furthermore I claim anything substantially the same. strung on a string or thread and applied to an atrificial globe, or applied in any manner Whatever to illustrate the rotation of the earth by the vibrations of a pendulum.

GEORGE M. DIMMOCK.

Witnesses:

R. A. CHAPMAN, N. W. TALCOTT.

I do not claim a ball suspended or 15 

